As is well known, friction clutches, which are disposed in a torque transmitting relationship between an internal combustion engine and a transmission, have a spring damper assembly which is operable to limit the transmission of torsional disturbances between the engine and the transmission. Spring damper assemblies generally have a plurality of caged spring members which are disposed between the input and output members of a damper. The caged spring members are limited in their travel, generally due to design. This travel limit controls the angular excursion permitted within the damper assembly. The limits of angular excursion are generally provided by rivet members which are secured to the spring cage and aligned with fingers or tabs on the output hub of the damper.
Also, as is well known, these damper assemblies include a frictional hysteresis characteristic. The frictional hysteresis is generally a result of friction plates disposed between adjacent members of the damper assembly which are relatively rotatable. The amount of friction hysteresis is controlled either by a spring member providing a normal force or by assembly forces which are present within the damper assembly. The more usual and consistent means of establishing the frictional hysteresis force is the use of a washer spring which compresses frictional plates between the adjacent members.